Method and device for end closure of packaging tubes

ABSTRACT

A method and apparatus for the end closure of packaging tubes is provided. In one embodiment, the tube which is to be sealed presents an intermediate wall having a surplus length across the tube cross-section, and the intermediate wall is fixed at the filling end of the tube to the tube wall and along two joining locations extending along the length of the tube. 
     A hot air nozzle with two sub-members forming a gap therebetween is inserted into the opening in the filling end, and parts of the intermediate wall and the inside of the tube intended for sealing are heat activated in a non-contacting manner. 
     Apparatus for producing a clamping action is pressed against the heat activated tube end and the intermediate wall. This apparatus includes a pair of clamping jaws arranged for translatory motion perpendicular to the tube axis and initially in a direction at an angle to a line through the joining locations.

FIELD OF THE INVENTION

The present invention relates to packaging tubes of the so-calledflexible type, i.e., tubes with a tube body manufactured from materialwhich allows the body to be squeezed for emptying the packagingcontents. More precisely,, the present invention relates to flexiblepackaging tubes with an intermediate wall which forms twoproduct-receiving compartments in the tube, the compartments beingseparated from one another.

Such packaging tubes are used for allowing the containment of differentproduct types as well as for delivering a mixture of the products whichis obtained in-situ.

The present invention is intended to provide a method and apparatus forend closure of such intermediate wall tubes, as distinguished from socalled twin tubes (see for instance applicant's own InternationalApplication No. WO 94119251).

BACKGROUND OF THE INVENTION

Tubes with intermediate walls are manufactured, inter alia, by startingfrom web-like flexible material, e.g., polyethylene, polypropylene orother thermoplastic materials, in a longitudinal direction, by joining,along a pair of welded seams, a material layer serving as an outer tubewall to a material layer serving as an intermediate wall, whichintermediate wall material layer is normally thinner than the outermaterial layer. The width of the outer material web is thereby largerthan the width of the material web which is intended to form theintermediate wall, and the relationship between the widths is oftenchosen so that after longitudinal sealing of the outer layer and formingthis into a circular tube, the intermediate wall presents a length overthe cross-section of the tube which exceeds the diameter of the tube.The length of the intermediate wall is often chosen so that itcorresponds to half the circumference of the tube, which means that withso-called planar sealing of the filling end of the tube, theintermediate wall presents the same length as the flattened tube endduring sealing, as well as afterwards.

It has, however, shown itself to be the case that this surplus of lengthin the intermediate wall, which can be advantageous in the ready-sealedtube end, results in difficulties, even at the filling stage.

In order to overcome this, the applicant previously produced a methodand device (WO 98/54054, priority date May 27, 1997), which allows theintroduction of the filling nozzle on respective sides of theintermediate wall. Two relatively well-defined spaces in the closure endof the packaging tube are thereby created by the intermediate wall beingstretched and spot welded to the inside of the tube at two substantiallydiametrically opposed positions.

This spot welding is done in a filling machine and, for continuedefficient handling in the machine after filling with product/products,the filling end of the tube with corresponding end of the intermediatewall has to be capable of being sealed in a rational manner to form anend closure.

Tubes with intermediate walls are also manufactured by injectionmolding, in one-piece, a tube body, breast and intermediate wall.

Due to this manufacturing method, the intermediate wall in this case isof a thicker material as compared to the first-mentioned type ofintermediate wall tube.

The greater material thickness results in problems with sealing the tubeend.

In order to achieve such sealing, the intermediate wall has been allowedto finish at a distance from the tube end. With the aid of contactingheated jaws, heat energy from the outside of the tube is supplied to theinside of the tube in an encircling end area of the tube at a levelabove the intermediate wall.

Thus, in the tube filling machine, directly after the heat-activationstation following the embossing station, embossing jaws operatingperpendicularly to the intermediate wall during the entire sealingprocess have been used to press the ends of the tube together in theencircling end area in order to thereby create a seal.

However, such a seal does not always ensure the production of a jointwhich is free of passages between the two product containingcompartments, which the intermediate wall is intended to achieve.

One object of the present invention is to solve the problem of endclosure of packaging tubes of the types mentioned above, and to providea solution which, while maintaining productivity in a tube fillingmachine, provides a complete handling of intermediate wall tubes, inprinciple in a manner which is equal to the highly effective handling ofconventional tubes.

The solution to these problems should furthermore be such that a minimumof disturbance is required in existing tube filling lines.

SUMMARY OF THE INVENTION

In accordance with the present invention, these and other objects havenow been realized by the discovery of a method for the end closure of apackaging tube including a tube body having a filling end and anintermediate wall forming a pair of separated product-receivingcompartments, the intermediate wall extending across the tube bodysubstantially along the entire length of the tube body along a firstpair of circumferentially spaced joining locations, and a second pair ofcircumferentially spaced joining locations at the filling end of thetube body, whereby predetermined portions of the intermediate wall areformed between each of the second pair of circumferentially spacedjoining locations and each of the first pair of circumferentially spacedjoining locations, the method comprising heat activating theintermediate wall and the inside of the tube body by inserting a hot airnozzle including a pair of sub-members forming a gap therebetween intothe area of the filling end of the tube body without direct contact withthe packaging tube while applying a forming tool externally to thefilling end of the tube body whereby the cross-sectional dimension ofthe filling end is compressed in both the horizontal and verticaldirections, the intermediate wall is maintained in a stretched conditionin the filling end of the tube body and both of the predeterminedportions of the intermediate wall are brought closer to the inside ofthe tube body than before application of the forming tool, subsequentlyremoving the hot air nozzle, and clamping the packaging tube so as toseal the filling end of the tube body.

In accordance with one embodiment of the method of the presentinvention, the tube body comprises a substantially elliptical shape andthe intermediate wall is stretched across a minor axis of the fillingend of the tube body, and wherein the applying of the forming toolexternally to the filling of the tube body provides a cross-sectionaldimension of the tube end having a substantially right-angled,four-sided shape. In a preferred embodiment, the pair of sub-members ofthe hot air nozzle comprise a pair of substantially identicalsub-members defining substantially a right-angled cross-sectionaldimension forming the gap adapted to receive the intermediate wall.

In accordance with another embodiment of the method of the presentinvention, the method includes inserting the hot air nozzle into thearea of the filling end of the tube body so that the concentration ofheat energy obtained on the intermediate wall is provided at portions ofthe intermediate wall between the first and second pairs ofcircumferentially spaced joining locations.

In accordance with the present invention, apparatus has also beendiscovered for the end closure of a packaging tube including a tube bodyhaving a filling end and an intermediate wall forming a pair ofseparated product-receiving compartments, the intermediate wallextending across the tube body substantially along the entire length ofthe tube body along a first pair of circumferentially spaced joininglocations and a second pair of circumferentially spaced joininglocations at the filling end of the tube body, whereby predeterminedportions of the intermediate wall are formed between each of the secondpair of circumferentially spaced joining locations and each of the firstpair of circumferentially spaced joining locations, the apparatuscomprising a hot air nozzle including a pair of sub-members forming agap therebetween for accommodating the intermediate wall, the pair ofsub-members including hot air delivery openings in the gap and outsideof the gap, the hot air nozzle being dimensioned for insertion into thefilling end of the tube body without directly contacting the packagingtube whereby the tube body including the intermediate wall at thefilling end can be heat activated, clamping means for clamping andsealing the heat activated regions of the tube body, and a forming toolfor external application to the filling end of the tube body during theheat activation to compress the filling end in both the horizontal andvertical directions, to maintain the intermediate wall in a stretchedcondition in the filling end of the tube body, and to bring both of thepredetermined portions of the intermediate wall closer to the inside ofthe tube body than before application of the forming tool. In apreferred embodiment, the forming tool includes cooling means, theforming tool including an inner surface providing a substantiallyfour-sided forming opening for application to the filling end of thetube body.

The solution to the problem underlying the present invention, whendealing with packaging tubes of the above-mentioned type, is found bythe realization that it is possible, in the present connection ofmaterial wall thicknesses of a highly varying degree and material ofdifferent types, as well as with addition of material layers indifferent areas of the produced sealing area, with the method andapparatus described above to heat-activate the complicated materialcomposite or geometry, respectively, so that acceptable heat sealing isobtained in all areas of the produced end closure, also including anyareas with double-layered intermediate walls and areas with up to andincluding triple intermediate walls.

The solution to the problems underlying the present invention, whendealing with the packaging tubes of the second type mentioned, is foundby the realization that it is possible, in the present connection ofmaterial wall thicknesses achievable by injection molding and with theintermediate wall finishing at the level of the tube end or at adistance from it, with the method and apparatus, respectively, toheat-activate and thereafter press together the complicated materialgeometry so that acceptable heat sealing is obtained in all areas of theend closure which is created, including also any areas where theintermediate wall is present.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top, elevational, partially schematic, cross-sectional viewof an intermediate wall tube as it appears after manufacture;

FIG. 2 is a top, elevational, partially schematic, cross-sectional viewof the tube of FIG. 1 with the intermediate wall fixed to the tube at apair of additional connections points;

FIG. 3 is a top, elevational, partially schematic, cross-sectional viewof the tube shown in FIG. 2, re-formed with a forming tool and with thetube in a position for heat activation of those surfaces of the tubematerial which are to be sealed together in a later stage;

FIG. 4a is a top, elevational, partially schematic, cross-sectional viewof the tube taken out of the forming tool in FIG. 3 and, shown witharrows, a possible compressing direction in the station in the fillingmachine where the closure is formed;

FIG. 4b is a top, elevational, partially schematic, cross-sectional viewof a second preferred compressing direction for the heat-activatablefilling end of the tube;

FIG. 5a is a top, elevational, partially schematic, cross-sectional viewof the tube and the intermediate wall during clamping according to FIG.4a, showing the material composition and geometry which is present;

FIG. 5b is a top, elevational, partially schematic, cross-sectional viewof the tube and the intermediate wall during compression according toFIG. 4b;

FIG. 6 is a bottom, elevational view of a first embodiment of twosub-members forming a hot air nozzle according to the present invention;

FIG. 7 is a side, elevational view of the nozzle shown in FIG. 6;

FIG. 8 is a side, perspective view of the nozzle shown in FIG. 6;

FIG. 9 is a bottom view of a second embodiment of a divided nozzle ofthe present invention with modified tube cross-section schematicallyadded;

FIG. 10 is a side view of the nozzle shown in FIG. 9;

FIG. 11 is a side view of the nozzle shown in FIG. 9;

FIG. 12 Is a top, elevational, partially schematic, cross-sectional viewof an intermediate wall tube, injection molded in one piece (with thetube breast not shown); and

FIG. 13 is a top, elevational, partially schematic, cross-sectional viewof the tube and the intermediate wall, while being clamped togetheraccording to FIG. 12.

DETAILED DESCRIPTION

The tube 10 schematically shown in FIG. 1 from the filling end includesin a traditional manner an end (not shown) comprising a tube breastprovided with an emptying orifice, and in the embodiment shown beingmanufactured from a flat blank and by means of longitudinal sealing 14being given a substantially circular cross-section. Depending on thetype of material of the tube body, where the material can be a monomermaterial of any suitable polyolefin, e.g., polyethylene, polypropylene,etc., or a laminate of plastic material with barrier properties or metalfoil or alternatively metallized film, the cross-section will have moreor less a predefined shape. Additionally, the damage or effects that arecaused by the conveyance of the tubes will effect the cross-section thatfinally ends up in the tube filling machine.

In the tube body 10 there is an intermediate wall 11 which is joined tothe planar tube body blank or tube body, respectively, by longitudinalseals, 12 and 13. The material of the intermediate wall 11 in theembodiment shown is of a material type which is heat sealable to thetube blank or the inside of the tube body, e.g., the material type maybe identical to the material of the tube body 10, or its inner layer, ifthe tube body 10 is formed of a laminate.

The intermediate wall 11 has a surplus of length which means that withinthe tube body 10 it describes approximately the curve which is shown inFIG. 1. The length often corresponds to half the circumference of thetube body 10, with the intention that when the tube filling end is in aflattened condition, opposing sections of the tube body and intermediatewall will present the same diametrical length.

As mentioned in the introduction, the surplus length of the intermediatewall results in problems of introducing the filling nozzle into thefilling end, such that in reality one has often resorted to stretchingthe intermediate wall 11 in the area of the filling opening inaccordance with that shown in FIG. 2. The intermediate wall 11 has, inthat case, been spot welded to the tube body wall adjacent the upperedge of the filling opening, or at a short distance therefrom, while theconnections, 12 and 13, still join the intermediate wall along theentire length of the tube body up into its tube breast and into theemptying orifice. By stretching the intermediate wall lithecross-section in FIG. 1 will be changed. The change in shape whichoccurs depends to a large extent on the elasticity of the tube bodymaterial. Due to the spot welding of the intermediate wall, thecross-sectional shape will normally assume an oval or elliptical form inaccordance with FIG. 2. The intermediate wall 11 can be more or lessstretched depending on the elasticity of the tube body material, and thedashed line 11′ depicts a case with deformed cross-section but with aslack intermediate wall 11′. The connections, 15 and 16, or theintermediate wall give rise to material portions, 11 a and 11 b, betweenrespective spot welds, 15 and 16, and the adjacent connection locations,12 and 13, at the tube wall. In practice it is difficult to lay thesematerial portions, 11 a and 11 b, closely against the inside of the tubewall, especially since the material properties of the tube wall canpresent a return action tendency back to the original form of FIG. 1,while the material in the thinner intermediate wall 11 does not have acorresponding tendency. The result is that between the intermediate wallportions, 11 a and 11 b, and the inside of the tube wall there will be aspace which makes uniform heat-activation of the intermediate wall andthe inside of the tube wall difficult. Moreover, as already mentioned,in certain applications the stretching of the intermediate wall 11 canbe insufficient for creating a well-defined geometry for heatactivation, which can additionally complicate the situation.

In such application use is made of a re-forming step, where a formingtool 17 with a forming opening 18 with a substantially right-angledfour-sided shape is applied to the outside of the tube body at thefilling end. By dimensioning this opening 18 in such a way that theopening deforms, i.e., presses together, the cross-sectional dimensionof the tube end in FIG. 2 in both the horizontal and verticaldirections, the sections, 11 a and 11 b, will be brought closer to theinside of the tube body and the intermediate wall 11 will be tightenedinto a stretched condition.

FIG. 3 shows such a condition. The dashed lines, 19 and 20, show a pairof non-contactingly operating sub members, 19 and 20, or a hot airnozzle for heat activation of those areas of the intermediate wall andthe inside of the tube which will later be put together as a tube endseal.

From the Figure it is clear that the cross-section of these sub-memberstogether form a substantially right-angled four-sided shape and thatthis right-angled quadrilateral (in the plane of the forming tool) hasabout the same orientation as the quadrilateral which is formed by thetube body end in the forming tool 17. By means of this well-definedmutual orientation between the sub-members of the nozzle and the tubecross-section, it is possible to empirically determine a heat activationsuitable for end closure of the mentioned different sections of theintermediate wall and the tube end which is to be sealed for forming theend closure. Moreover, it is possible to vary the distance as well asthe hot air release from activation location to activation location forthe non-contacting heat activation, whereby the heat transfer in e.g.,the positions, 11 a and 11 b, for double material layers (theintermediate wall and the tube wall in FIG. 3) can be intensified byreducing the distance and/or increasing the release of hot air.

With a gap 21 between the sub-elements, 19 and 20, it is possible (alsoempirically) to control the heat transfer to both sides of theintermediate wall 11.

The forming tool 17 also serves to externally control temperatureconditions of the tube body at its sealing end, by the tool beingconnected to a cooling medium inlet 22 for circulation of a coolingmedium, e.g., water, through an encircling channel 23.

The forming tool 17 and the hot air nozzle 24 comprising thesub-members, 19 and 20, is arranged in a heat activation station (notshown) in the tube filling machine. Filled tubes are then intermittentlyfed to this station, and the filling end of a tube present in thestation is contacted by the forming tool 17 and after re-forming the hotair nozzle's sub-members, 19 and 20, will be located in the positionwhich is depicted in FIG. 3 and which is also shown in FIG. 9.

After heat activation is carried out according to FIG. 3, the tube isreleased from the heat activation station and is conveyed further to aclamping jaw station where its clamping jaws (embossing jaws) achieveclamping of the tube end in accordance with the arrows, 25 and 26 (FIGS.4a, 4 b).

As is clear from FIG. 5a, the intermediate wall 11 in this embodiment islaid together to form a total of three layers, where also the outerlayer is to be put together with the inside of the tube, where the outerlayer is also to be put together with the inside of the tube wall. It isthus essential that the heat activation produced according to FIG. 3achieves sufficient heat activation for acceptable heat sealing in allsections.

In the embodiment according to FIG. 5b the build up of layers is easierto handle from a sealing point of view. The intermediate wall here liesas a single layer in the area of the tube end.

With the described embodiment of the hot air nozzle and the formingtool, the conditions for sufficient heat activation are determinedempirically.

In certain applications where the conditions are favorable, especiallyconcerning the material of the intermediate wall and the tube body, itis possible to omit the re-forming step and to use a hot air nozzledesign of FIGS. 6-8. In this special case, there is still a gap 21 aintended to receive the intermediate wall 11, and the sub-members, 19 aand 20 a, are so designed that non-contacting heat activation ispossible. Even in this latter case, the design of gap 21 a as well asthe outer contour of the sub-members 19 a, 20 a is determined in anempirical manner.

So far the present invention has been described in connection with aspecific embodiment of a packaging tube. However, as mentioned in theintroduction, it is understood that the present invention may also beapplied in other areas, for example in applications where the tube andintermediate wall are manufactured in one piece by injection molding orin a similar manner.

The tube 10, schematically shown in FIG. 12 from the filling end,includes in a traditional manner an end (not shown) comprising a tubebreast provided with an emptying orifice, and in the embodiment shownbeing manufactured by injection molding and being given a substantiallycircular cross-section.

In the tube body 10 there is an intermediate wall 11 which is formed asone piece with the tube body by injection molding and is connected tothis at connection locations, 12 and 13. The intermediate wall extendsinto the tube breast and there delimits two separate delivery passagesall the way up to the emptying ends. At the other end of the tube body,the intermediate wall extends into the end edge of the tube body orfinishes at a particular, predetermined distance from this end edge.

FIG. 12 indicates in dashed lines, 19 and 20, a pair of non-contactinglyoperating sub-members, 19 and 20, of a hot air nozzle for heatactivation of those areas of the intermediate wall and of the inside ofthe tube which are later to be put together to form a tube end seal.

From this figure it is clear that the cross-section of these sub-memberssubstantially corresponds to the cross-section of the sub-compartmentsof the tube formed by the intermediate wall. By means of thiswell-defined form of the sub-members and the respective orientationbetween the sub-members of the nozzle and the tube cross-section, anempirically determinable heat activation suitable for end sealing of thesections of the intermediate wall and the tube ends which are to besealed for forming the end closure is made possible. By means of theform and the placement of openings for hot air release, it is possibleto vary the distance as well as the hot air release from activationlocation to activation location for the contactless heat activation.

With a gap 21 between the sub-members, 19 and 20, the heat transfer toboth sides of the intermediate wall 11 can (also empirically) becontrolled.

The hot air nozzle 24, including the sub-members, 19 and 20, is arrangedin a heat activation station (not shown) in a tube filling machine.Filled tubes are thereby fed intermittently to this station, and in thisposition a filling end of a tube present in the station is heatactivated by the sub-members 19, 20 of the hot air nozzle, as shown inFIG. 12.

After heat activation has been performed according to FIG. 12, the tubeis removed from the heat activation station and transported further to aclamping jaw station where its clamping jaws (embossing jaws) achieve asquashing of the tube end in accordance with the arrows, 25 and 26.

As shown by these arrows, the clamping jaws or embossing jaws actagainst the outside of the tube body and perform a movement by which thetube body is pressed by a pair of opposed jaws, which after pressingagainst the tube body perform opposed translatory movement in a planeperpendicular to the longitudinal axis of the tube, in the direction ofarrows, 25 and 26, i.e., initially in a direction at an angle to theextension of the intermediate wall.

By means of this initial “angled” pressing, the circular cross-sectionis progressively changed (step 2) to a planar seal with the intermediatewall included in the seal or (depending on the extent of theintermediate wall in the longitudinal direction of the tube) with itsupper edge directly merging into this, in order to separate, without anypassages, the two compartments which are formed by the intermediatewall.

The initial pressing of the embossing or clamping jaws thus allows theintermediate form shown in FIG. 13 to be laid flat in the final stage,with the intermediate wall securely positioned within the end seal or indirect connection in a passage-free manner relative to this.

Although the present invention has been described in connection withspecific embodiments of packaging tubes, it is understood that thepresent invention may also be applied in other areas, for example, wherean intermediate wall does not extend in a straight line across the tubecross-section, but instead in an 5-formed manner, for example. For this,the sub-members of the nozzle are given a corresponding cross-sectionand the initial pressing direction for the clamping jaws is therebydefined in relation to an imaginary straight joining line between theconnection locations with the tube body.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

What is claimed is:
 1. A method for the end closure of a packaging tubeincluding a tube body having a filling end and an intermediate wallforming a pair of separated product-receiving compartments, saidintermediate wall extending across said tube body substantially alongthe entire length of said tube body along a first pair ofcircumferentially spaced joining locations, and a second pair ofcircumferentially spaced joining locations at said filling end of saidtube body, whereby predetermined portions of said intermediate wall areformed between each of said second pair of circumferentially spacedjoining locations and each of said first pair of circumferentiallyspaced joining locations, said method comprising heat activating saidintermediate wall and the inside of said tube body by inserting a hotair nozzle including a pair of sub-members forming a gap therebetweeninto said area of said filling end of said tube body without directcontact with said packaging tube while applying a forming toolexternally to said filling end of said tube body whereby thecross-sectional dimension of said filling end is compressed in both thehorizontal and vertical directions, said intermediate wall is maintainedin a stretched condition in said filling end of said tube body and bothof said predetermined portions of said intermediate wall are broughtcloser to the inside of said tube body than before application of saidforming tool, subsequently removing said hot air nozzle, and clampingsaid packaging tube so as to seal said filling end of said tube body. 2.The method according to claim 1 wherein said tube body comprises asubstantially elliptical shape and said intermediate wall is stretchedacross a minor axis of said filling end of said tube body, and whereinsaid applying of said forming tool externally to said filling of saidtube body provides a cross-sectional dimension of said tube end having asubstantially right-angled, four-sided shape.
 3. The method according toclaim 2 wherein said pair of sub-members of said hot air nozzle comprisea pair of substantially identical sub-members defining substantially aright-angled cross-sectional dimension forming said gap adapted toreceive said intermediate wall.
 4. The method according to claim 3including inserting said hot air nozzle into said area of said fillingend of said tube body so that the concentration of heat energy obtainedon said intermediate wall is provided at portions of said intermediatewall between said first and second pairs of circumferentially spacedjoining locations.
 5. Apparatus for the end closure of a packaging tubeincluding a tube body having a filling end and an intermediate wallforming a pair of separated product-receiving compartments, saidintermediate wall extending across said tube body substantially alongthe entire length of said tube body along a first pair ofcircumferentially spaced joining locations and a second pair ofcircumferentially spaced joining locations at said filling end of saidtube body, whereby predetermined portions of said intermediate wall areformed between each of said second pair of cumferentially spaced joininglocations and each of said first pair of circumferentially spacedjoining locations, said apparatus comprising a hot air nozzle includinga pair of sub-members forming a gap therebetween for accommodating saidintermediate wall, said pair of sub-members including hot air deliveryopenings in said gap and outside of said gap, said hot air nozzle beingdimensioned for insertion into said filling end of said tube bodywithout directly contacting said packaging tube whereby said tube bodyincluding said intermediate wall at said filling end can be heatactivated, clamping means for clamping and sealing said heat activatedregions of said tube body, and a forming tool for external applicationto said filling end of said tube body during said heat activation tocompress said filling end in both the horizontal and verticaldirections, to maintain the intermediate wall in a stretched conditionin said filling end of said tube body, and to bring both of saidpredetermined portions of said intermediate wall closer to the inside ofsaid tube body than before application of said forming tool.
 6. Theapparatus of claim 5, wherein said forming tool includes cooling means,said forming tool including an inner surface providing a substantiallyfour-sided forming opening for application to said filling end of saidtube body.